Nanoparticle compositions and greaseless coatings for equipment

ABSTRACT

A composition that includes solid lubricant nanoparticles and an organic medium is disclosed. Also disclosed are nanoparticles that include layered materials. A method of producing a nanoparticle by milling layered materials is provided. Also disclosed is a method of making a lubricant, the method including milling layered materials to form nanoparticles and incorporating the nanoparticles into a base to form a lubricant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application and claims thebenefit of the filing date under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 13/921,640, filed on Jun. 19, 2013. U.S. patentapplication Ser. No. 13/921,640 is a continuation application and claimsthe benefit of the filing date under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 12/160,758, filed on Sep. 2, 2008, now U.S. Pat.No. 8,492,319 which issued on Jul. 23, 2013. U.S. patent applicationSer. No. 12/160,758 is a national stage filing under 35 U.S.C. §371 andclaims priority to International Application No. PCT/US2007/060506,filed on Jan. 12, 2007. International Application No. PCT/US2007/060506claims priority under 35 U.S.C. §119(e) to U.S. Provisional PatentApplication No. 60/758,307, filed on Jan. 12, 2006. The contents of U.S.patent application Ser. No. 13/921,640, U.S. patent application Ser. No.12/160,758, International Application No. PCT/US2007/060506, and U.S.Provisional Patent Application No. 60/758,307 are hereby incorporated byreference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with U.S. government support under grant numberNSF/DMI 0115532 awarded in part by the National Science Foundation. TheU.S. government has certain rights in the invention.

BACKGROUND

Over the years, considerable effort has been expended to developnanostructures that can be used as lubricants, coatings, or deliverymechanisms. New ways to improve nanoparticle compositions, their methodof manufacture, and their use are sought.

SUMMARY

In one aspect, a composition is described, comprising solid lubricantnanoparticles and an organic medium.

In another aspect, nanoparticles comprising a layered material aredisclosed.

In a further aspect, a method of producing a nanoparticle comprisingmilling layered materials is provided.

In yet another aspect, a method of making a lubricant is disclosed, inwhich the method comprises milling layered materials to formnanoparticles and incorporating the nanoparticles into a base to form alubricant.

Other aspects will become apparent by consideration of the detaileddescription and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a method of producing solid lubricantnanoparticles.

FIG. 2 is a diagram illustrating one method of preparing nanoparticlebased lubricants.

FIG. 3 shows transmission electron microscopy (TEM) micrographs ofmolybdenum disulfide particles. Panel (A) shows molybdenum disulfide asit is available, typically from about a few microns to submicron size.Panel (B) shows molybdenum disulfide that has been ball milled in airfor 48 hours. Panel (C) is a high resolution electron microscopy imagethat shows molybdenum disulfide that has been ball milled in air for 48hours. Panel (D) is a high-resolution transmission electron microscopy(HRTEM) image that shows molybdenum disulfide that has been ball milledin air for 48 hours followed by ball milling in oil for 48 hours.

FIG. 4 is a graph showing XRD spectra of molybdenum disulfide particles.Line (A) is the XRD spectra for molybdenum disulfide that has been ballmilled in air for 48 hours followed by ball milling in oil for 48 hours.Line (B) is the XRD spectra for molybdenum disulfide that has been ballmilled in air for 48 hours. Line (C) is the XRD spectra for molybdenumdisulfide that has not been ball milled.

FIG. 5 is a graph showing XPS spectra of molybdenum disulfide particlesin which the carbon peak for molybdenum disulfide that has not been ballmilled is shown, as well as the carbon peak for molybdenum disulfidethat has been ball milled in air for 48 hours, followed by ball millingin oil for 48 hours.

FIGS. 6(A)-6(D) show graphs and bar charts depicting tribological testdata for different additives in paraffin oil. FIG. 6(A) shows theaverage wear scar diameter for a base oil (paraffin oil), paraffin oilwith micron sized MoS₂, paraffin oil with MoS₂ that was milled in airfor 48 hours, and paraffin oil with MoS₂ that was milled in air for 48hours followed by milling in canola oil for 48 hours. FIG. 6(B) showsthe load wear index for paraffin oil without a nanoparticle additive,paraffin oil with micron sized MoS₂, paraffin oil with MoS₂ that wasmilled in air for 48 hours, and paraffin oil with MoS₂ that was milledin air for 48 hours followed by milling in canola oil for 48 hours. FIG.6(C) shows the coefficient of friction for paraffin oil without ananoparticle additive, paraffin oil with micron sized MoS₂ (c-MoS₂),paraffin oil with MoS₂ that was milled in air for 48 hours (d-MoS₂), andparaffin oil with MoS₂ that was milled in air for 48 hours followed bymilling in canola oil for 48 hours (n-MoS₂). FIG. 6(D) shows the extremepressure data for paraffin oil with micron sized MoS₂ (c-MoS₂), paraffinoil with MoS₂ that was milled in air for 48 hours (d-MoS₂), and paraffinoil with MoS₂ that was milled in air for 48 hours followed by milling incanola oil for 48 hours (n-MoS₂); in each test the solid lubricantnanoparticle additive was present in the amount of 1% by weight.

FIG. 7 is a TEM image showing the architecture of molybdenum disulfidenanoparticles (15-70 nm average size). Panel (a) shows the close cageddense oval shaped architecture of molybdenum disulfide nanoparticlesthat have been ball milled in air for 48 hours. Panel (b) shows the openended oval shaped architecture of molybdenum disulfide nanoparticlesthat have been ball milled in air for 48 hours followed by ball millingin canola oil for 48 hours.

FIG. 8 is a graph depicting a comparison of wear scar diameters fordifferent additives in paraffin oil. One additive is crystallinemolybdenum disulfide (c-MoS₂). Another is molybdenum disulfidenanoparticles that were ball milled in air (n-MoS₂). Another additive ismolybdenum disulfide nanoparticles that were ball milled in air followedby ball milling in canola oil and to which a phospholipid emulsifier wasadded (n-MoS₂+Emulsifier).

FIG. 9 shows photographs and graphs produced using energy dispersivex-ray analysis (EDS) depicting the chemical analysis of wear scardiameters in four-ball tribological testing for nanoparticle basedlubricants. Panel (a) shows paraffin oil without any nanoparticlecomposition additive. Panel (b) shows paraffin oil with molybdenumdisulfide nanoparticles that have been ball milled in air for 48 hoursfollowed by ball milling in oil for 48 hours and treated with aphospholipid emulsifier.

DETAILED DESCRIPTION

Before any embodiments are explained in detail, it is to be understoodthat the invention is not limited in its application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the following drawings. Theinvention is capable of other embodiments and of being practiced or ofbeing carried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting.

Any numerical range recited herein includes all values from the lowervalue to the upper value. For example, if a concentration range isstated as 1% to 50%, it is intended that values such as 2% to 40%, 10%to 30%, or 1% to 3%, etc., are expressly enumerated in thisspecification. These are only examples of what is specifically intended,and all possible combinations of numerical values between and includingthe lowest value and the highest value enumerated are to be consideredto be expressly stated in this application.

Herein described are compositions and methods for making compositionscomprising solid lubricant nanoparticles and an organic medium. Alsodescribed are nanoparticles comprising layered materials. Thenanoparticles may be solid lubricant nanoparticles. The nanoparticlesmay be made from starting materials or solid lubricant startingmaterials. Examples of solid lubricants may include, but are not limitedto, layered materials, suitably chalcogenides, more suitably, molybdenumdisulphide, tungsten disulphide, or a combination thereof. Anothersuitable layered material is graphite or intercalated graphite. Othersolid lubricants that may be used alone or in combination with thelayered materials are polytetrafluoroethylene (Teflon®), boron nitride(suitably hexagonal boron nitride), soft metals (such as silver, lead,nickel, copper), cerium fluoride, zinc oxide, silver sulfate, cadmiumiodide, lead iodide, barium fluoride, tin sulfide, zinc phosphate, zincsulfide, mica, boron nitrate, borax, fluorinated carbon, zinc phosphide,boron, or a combination thereof. Fluorinated carbons may be, withoutlimitation, carbon-based materials such as graphite which has beenfluorinated to improve its aesthetic characteristics. Such materials mayinclude, for example, a material such as CF.sub.x wherein x ranges fromabout 0.05 to about 1.2. Such a material is produced by Allied Chemicalunder the trade name Accufluor.

The methods may include milling a solid lubricant feed. In oneembodiment, the solid lubricant feed may be capable of being milled toparticles comprising an average dimension of about 500 nanometers(submicron size) to about 10 nanometers. Suitably, the particles mayhave an average particle dimension of less than or equal to about 500nanometers, suitably less than or equal to about 100 nanometers,suitably less than or equal to about 80 nanometers, and more suitablyless than or equal to about 50 nanometers. Alternatively, the ballmilling may result in milled solid lubricant particles comprising amixture, the mixture comprising particles having an average particledimension of less than or equal to about 500 nanometers, plus largerparticles. Milling may include, among other things, ball milling andchemo mechanical milling. Examples of ball milling may include dry ballmilling, wet ball milling, and combinations thereof. Ball milling mayrefer to an impaction process that may include two interacting objectswhere one object may be a ball, a rod, 4 pointed pins (jack shape), orother shapes. Chemo mechanical milling may refer to an impaction processthat may form a complex between an organic medium and a nanoparticle. Asa result of chemo mechanical milling, the organic medium may coat,encapsulate, or intercalate the nanoparticles.

In another embodiment, the solid lubricant feed may be dry milled andthen wet milled. An emulsifier may be mixed with a base and added to thewet milled particles. Dry milling may refer to particles that have beenmilled in the presence of a vacuum, a gas, or a combination thereof. Wetmilling may refer to particles that have been milled in the presence ofa liquid.

The solid lubricant nanoparticle composition may further comprise anorganic medium. Examples of organic mediums include, but are not limitedto, oil mediums, grease mediums, alcohol mediums, or combinationsthereof. Specific examples of organic mediums include, but are notlimited to, composite oil, canola oil, vegetable oils, soybean oil, cornoil, ethyl and methyl esters of rapeseed oil, distilled monoglycerides,monoglycerides, diglycerides, acetic acid esters of monoglycerides,organic acid esters of monoglycerides, sorbitan, sorbitan esters offatty acids, propylene glycol esters of fatty acids, polyglycerol estersof fatty acids, n-hexadecane, hydrocarbon oils, phospholipids, or acombination thereof. Many of these organic media may be environmentallyacceptable.

The composition may contain emulsifiers, surfactants, or dispersants.Examples of emulsifiers may include, but are not limited to, emulsifiershaving a hydrophilic-lipophilic balance (HLB) from about 2 to about 7;alternatively, a HLB from about 3 to about 5; or alternatively, a HLB ofabout 4. Other examples of emulsifiers may include, but are not limitedto, lecithins, soy lecithins, phospholipids lecithins, detergents,distilled monoglycerides, monoglycerides, diglycerides, acetic acidesters of monoglycerides, organic acid esters of monoglycerides,sorbitan esters of fatty acids, propylene glycol esters of fatty acids,polyglycerol esters of fatty acids, compounds containing phosphorous,compounds containing sulfur, compounds containing nitrogen, or acombination thereof.

A method of making a lubricant is described. The composition may be usedas an additive dispersed in a base. Examples of bases may include, butare not limited to, oils, greases, plastics, gels, sprays, or acombination thereof. Specific examples of bases may include, but are notlimited to, hydrocarbon oils, vegetable oils, corn oil, peanut oil,canola oil, soybean oil, mineral oil, paraffin oils, synthetic oils,petroleum gels, petroleum greases, hydrocarbon gels, hydrocarbongreases, lithium based greases, fluoroether based greases,ethylenebistearamide, waxes, silicones, or a combination thereof.

Described herein is a method of lubricating or coating an object that ispart of an end application with a composition comprising at least one ofsolid lubricant nanoparticles and an organic medium. Further describedis a method of lubricating an object by employing the compositioncomprising solid lubricant nanoparticles and an organic medium as adelivery mechanism.

Disclosed herein are compositions and methods of preparing nanoparticlebased lubricants that, among various advantages, display enhanceddispersion stability and resistance to agglomeration. FIG. 1 illustratesa method of preparing nanoparticle based lubricants or compositions. Asolid lubricant feed is introduced via line 210 to a ball millingprocessor 215. Ball milling is carried out in the processor 215 and thesolid lubricant feed is milled to comprise particles having an averageparticle dimension of less than or equal to about 500 nanometers,suitably less than or equal to about 100 nanometers, suitably less thanor equal to about 80 nanometers, and more suitably less than or equal toabout 50 nanometers. Alternatively, the ball milling may result inmilled solid lubricant particles comprising a mixture, the mixturecomprising particles having an average particle dimension of less thanor equal to about 500 nanometers, plus larger particles. The ballmilling may be high energy ball milling, medium energy ball milling, orcombinations thereof. Additionally, in various embodiments the ballmilling may be carried out in a vacuum, in the presence of a gas, in thepresence of a liquid, in the presence of a second solid, or combinationsthereof. The nanoparticle composition may be removed from the processorvia line 220. The nanoparticle composition may be a nanoparticle basedlubricant.

In alternative embodiments, the ball milling may comprise a first ballmilling and at least one more subsequent ball millings, or ball millingand/or other processing as appropriate. Suitably, the ball milling maycomprise dry milling followed by wet milling. FIG. 2 illustrates afurther method 100 of preparing nanoparticle based lubricants where drymilling is followed by wet milling. Feed 110 introduces a solidlubricant feed into a ball milling processor 115 where dry ball milling,such as in a vacuum or in air, reduces the solid lubricant feed toparticles having an average dimension of the size described above. Line120 carries the dry milled particles to a wet milling processor 125. Vialine 160 the dry milled particles are combined with a composite oil oran organic medium prior to entering the wet milling processor 125.Alternatively, the organic medium and dry milled particles may becombined in the wet milling processor 125. In further alternativeembodiments (not shown), the dry milling and wet milling may be carriedout in a single processor where the organic medium is supplied to thesingle processor for wet milling after initially carrying out drymilling. In other alternative embodiments, the balls in the ball millingapparatus may be coated with the organic medium to incorporate theorganic medium in the solid lubricant nanoparticles.

After wet milling, line 130 carries the wet milled particles to acontainer 135, which may be a sonication device. Alternatively, line 130may carry a mixture comprising solid lubricant nanoparticles, organicmedium, and a complex comprising the solid lubricant nanoparticlescombined with an organic medium.

In another embodiment, prior to introduction of the wet milled particlesinto the container 135, a base may be fed to the container 135 via line150. Alternatively, the base may be supplied to the wet millingprocessor 125 and the mixing, which may include sonicating, may becarried out in the wet milling processor 125. In such embodiments thesolid lubricant nanoparticle composition may be employed as an additiveand dispersed in the base. A base may be paired with a solid lubricantnanoparticle composition according to the ability of the base and thesolid lubricant nanoparticle composition to blend appropriately. In suchcases the solid lubricant nanoparticle composition may enhanceperformance of the base.

In a further embodiment, an emulsifier may be mixed with the base.Emulsifiers may further enhance dispersion of the solid lubricantnanoparticle composition in the base. The emulsifier may be selected toenhance the dispersion stability of a nanoparticle composition in abase. An emulsifier may also be supplied to the container 135 via line140. In many embodiments, the emulsifier and base are combined in thecontainer 135 prior to introduction of the wet milled particles. Priormixing of the emulsifier with the base may enhance dispersion uponaddition of complexes of solid lubricant nanoparticles and organicmedium and/or solid lubricant nanoparticles by homogeneouslydispersing/dissolving the complexes/nanoparticles. In some embodiments,the mixing of the emulsifier and base may comprise sonicating.Alternatively, the emulsifier may be supplied to the wet millingprocessor 125 and the mixing, which may include sonicating, may becarried out in the wet milling processor 125. The lubricant removed fromthe container 135 via line 120 may be a blend comprising the wet milledparticles, organic medium, and base. The blend may further comprise anemulsifier. In other alternative embodiments, additives may be added tothe nanoparticle based lubricant during interaction with a matingsurface.

In a further embodiment, antioxidants or anticorrosion agents may bemilled with the solid lubricant nanoparticles. Examples of antioxidantsinclude, but are not limited to, hindered phenols, alkylated phenols,alkyl amines, aryl amines, 2,6-di-tert-butyl-4-methylphenol,4,4′-di-tert-octyldiphenylamine, tert-Butyl hydroquinone,tris(2,4-di-tert-butylphenyl)phosphate, phosphites, thioesters, or acombination thereof. Examples of anticorrosion agents include, but arenot limited to, alkaline-earth metal bisalkylphenolsulphonates,dithiophosphates, alkenylsuccinic acid half-amides, or a combinationthereof. In another embodiment, biocidals may be milled with the solidlubricant nanoparticles. Examples of biocidals may include, but are notlimited to, alkyl or kydroxylamine benzotriazole, an amine salt of apartial alkyl ester of an alkyl, alkenyl succinic acid, or a combinationthereof.

In yet another embodiment, further processing of wet milled particlesmay comprise removal of oils that are not a part of a complex with thesolid lubricant particles. Such methods may be suitable for applicationsthat benefit from use of dry particles of solid lubricant, such ascoating applications. Oil and/or other liquids can be removed from wetmilled particles to produce substantially dry solid lubricant particlesand complexes. Such wet milling followed by drying may produce a solidlubricant with reduced tendency to agglomerate. In specific embodiments,an agent, such as acetone, can be added that dissolves oils that are nota part of a complex, followed by a drying process such as supercriticaldrying, to produce a substantially dry solid lubricant comprisingparticles treated by milling in an organic medium.

Ball milling conditions may vary and, in particular, conditions such astemperature, milling time, and size and materials of the balls and vialsmay be manipulated. In various embodiments, ball milling may be carriedout from about 12 hours to about 50 hours, suitably from about 36 hoursto about 50 hours, suitably from about 40 hours to about 50 hours, andmore suitably at about 48 hours. Suitably, ball milling is conducted atroom temperature. The benefits of increasing milling time may compriseat least one of increasing the time for the organic medium and solidlubricant nanoparticles to interact; and producing finer sizes, betteryield of nanoparticles, more uniform shapes, and more passive surfaces.An example of ball milling equipment suitable for carrying out thedescribed milling includes the SPEX CertiPrep model 8000D, along withhardened stainless steel vials and hardened stainless steel grindingballs, but any type of ball milling apparatus may be used. In oneembodiment, a stress of 600-650 MPa, a load of 14.9 N, and a strain of10⁻³-10⁻⁴ per sec may be used.

The proportions of the components in a nanoparticle based lubricant maycontribute to performance of the lubricant, such as the lubricantsdispersion stability and ability to resist agglomeration. In wetmilling, suitable ratios of solid lubricant nanoparticles to organicmedium may be about 1 part particles to about 4 parts organic medium byweight, suitably, about 1 part particles to about 3 parts organic mediumby weight, suitably, about 3 parts particles to about 8 parts organicmedium by weight, suitably, about 2 parts particles to about 4 partsorganic medium by weight, suitably, about 1 part particles to about 2parts organic medium by weight, and suitably, about 1 part particles toabout 1.5 parts organic medium by weight.

Suitable ratios of organic medium to emulsifier in a lubricant includingthe solid lubricant nanoparticles may be about 1 part organic medium toless than or equal to about 1 part emulsifier, suitably, about 1 partorganic medium to about 0.5 parts emulsifier by weight, or suitably,from about 0.4 to about 1 part emulsifier for about 1 part organicmedium by weight.

The amount of solid lubricant nanoparticle composition (by weight)sonicated or dispersed in the base may be from about 0.25% to about 5%,suitably 0.5% to about 3%, suitably 0.5% to about 2%, and more suitably0.75% to about 2%.

The amount of emulsifier (by weight) sonicated or dissolved in the base,depending on the end application, shelf-life, and the like, may be fromabout 0.5% to about 10%, suitably from about 4% to about 8%, suitablyfrom about 5% to about 6%, and suitably, from about 0.75% to about2.25%.

The solid lubricant nanoparticle composition may be used, withoutlimitation, as lubricants, coatings, delivery mechanisms, or acombination thereof. The solid lubricant nanoparticle composition may beused, without limitation, as an additive dispersed in a base oil. Thecomposition may also be used, without limitation, to lubricate aboundary lubrication regime. A boundary lubrication regime may be alubrication regime where the average oil film thickness may be less thanthe composite surface roughness and the surface asperities may come intocontact with each other under relative motion. During the relativemotion of two surfaces with lubricants in various applications, threedifferent lubrication stages may occur, and the boundary lubricationregime may be the most severe condition in terms of temperature,pressure and speed. Mating parts may be exposed to severe contactconditions of high load, low velocity, extreme pressure (for example,1-2 GPa), and high local temperature (for example, 150-300 degrees C.).The boundary lubrication regime may also exist under lower pressures andlow sliding velocities or high temperatures. In the boundary lubricationregime, the mating surfaces may be in direct physical contact. Thecomposition may further be used, without limitation, as a lubricant orcoating in machinery applications, manufacturing applications, miningapplications, aerospace applications, automotive applications,pharmaceutical applications, medical applications, dental applications,cosmetic applications, food product applications, nutritionalapplications, health related applications, bio-fuel applications or acombination thereof. Specific examples of uses in end applicationsinclude, without limitation, machine tools, bearings, gears, camshafts,pumps, transmissions, piston rings, engines, power generators,pin-joints, aerospace systems, mining equipment, manufacturingequipment, or a combination thereof. Further specific examples of usesmay be, without limitation, as an additive in lubricants, greases, gels,compounded plastic parts, pastes, powders, emulsions, dispersions, orcombinations thereof. The composition may also be used as a lubricantthat employs the solid lubricant nanoparticle composition as a deliverymechanism in pharmaceutical applications, medical applications, dentalapplications, cosmetic applications, food product applications,nutritional applications, health related applications, bio-fuelapplications, or a combination thereof. The various compositions andmethods may also be used, without limitation, in hybridinorganic-organic materials. Examples of applications usinginorganic-organic materials, include, but are not limited to, optics,electronics, ionics, mechanics, energy, environment, biology, medicine,smart membranes, separation devices, functional smart coatings,photovoltaic and fuel cells, photocatalysts, new catalysts, sensors,smart microelectronics, micro-optical and photonic components andsystems for nanophotonics, innovative cosmetics, intelligent therapeuticvectors that combined targeting, imaging, therapy, and controlledrelease of active molecules, and nanoceramic-polymer composites for theautomobile or packaging industries.

In some embodiments, the ball milling process may create a close cageddense oval shaped architecture (similar to a football shape or fullerenetype architecture). This may occur when molybdenum disulphide is milledin a gas or vacuum. Panel (a) of FIG. 7 shows the close caged dense ovalshaped architecture of molybdenum disulphide nanoparticles that havebeen ball milled in air for 48 hours.

In other embodiments, the ball milling process may create an open endedoval shaped architecture (similar to a coconut shape) of molybdenumdisulphide nanoparticles which are intercalated and encapsulated with anorganic medium and phospholipids. This may occur when molybdenumdisulphide is milled in a gas or vacuum followed by milling in anorganic medium. Panel (b) of FIG. 7 shows the open ended oval shapedarchitecture of molybdenum disulphide nanoparticles that have been ballmilled in air for 48 hours followed by ball milling in canola oil for 48hours.

As shown in the examples, the tribological performance of thenanoparticle based lubricant may be improved. The tribologicalperformance may be measured by evaluating different properties. Ananti-wear property may be a lubricating fluid property that has beenmeasured using the industry standard Four-Ball Wear (ASTM D4172) Test.The Four-Ball Wear Test may evaluate the protection provided by an oilunder conditions of pressure and sliding motion. Placed in a bath of thetest lubricant, three fixed steel balls may be put into contact with afourth ball of the same grade in rotating contact at preset testconditions. Lubricant wear protection properties may be measured bycomparing the average wear scars on the three fixed balls. The smallerthe average wear scar, the better the protection. Extreme pressureproperties may be lubricating fluid properties that have been measuredusing the industry standard Four-Ball Wear (ASTM D2783) Test. This testmethod may cover the determination of the load-carrying properties oflubricating fluids. The following two determinations may be made: 1)load-wear index (formerly Mean-Hertz load) and 2) weld load (kg). Theload-wear index may be the load-carrying property of a lubricant. It maybe an index of the ability of a lubricant to minimize wear at appliedloads. The weld load may be the lowest applied load in kilograms atwhich the rotating ball welds to the three stationary balls, indicatingthe extreme pressure level that the lubricants can withstand. The higherthe weld point scores and load wear index values, the better theanti-wear and extreme pressure properties of a lubricant. Thecoefficient of friction (COF) may be a lubricating fluid property thathas been measured using the industry standard Four-Ball Wear (ASTMD4172) Test. COF may be a dimensionless scalar value which describes theratio of the force of friction between two bodies and the force pressingthem together. The coefficient of friction may depend on the materialsused. For example, ice on metal has a low COF, while rubber on pavementhas a high COF. A common way to reduce friction may be by using alubricant, such as oil or water, which is placed between two surfaces,often dramatically lessening the COF.

The composition may have a wear scar diameter of about 0.4 mm to about0.5 mm. The composition may have a COF of about 0.06 to about 0.08. Thecomposition may have a weld load of about 150 kg to about 350 kg. Thecomposition may have a load wear index of about 20 to about 40. Thevalues of these tribological properties may change depending on theamount of solid lubricant nanoparticle composition sonicated ordissolved in the base.

Various features and aspects of the invention are set forth in thefollowing examples, which are intended to be illustrative and notlimiting.

EXAMPLES Example 1

Ball milling was performed in a SPEX 8000D machine using hardenedstainless steel vials and balls. MoS₂ (Alfa Aesar, 98% pure, 700 nmaverage primary particle size) and canola oil (Crisco) were used as thestarting materials in a ratio of 1 part MoS₂ (10 grams) to 2 partscanola oil (20 grams). The ball to powder weight ratio was 2 to 1. MoS₂was ball milled for 48 hours in air followed by milling in canola oilfor 48 hrs at room temperature. The nanoparticles were about 50 nm afterball milling. Table 1 summarizes milling conditions and resultantparticle morphologies. It was observed that there was a strong effect ofmilling media on the shape of the ball milled nanoparticles. Dry millingshowed buckling and folding of the planes when the particle size wasreduced from micron size to nanometer size. However, the dry millingcondition used here produced micro clusters embedding severalnanoparticles. On the other hand, wet milling showed no buckling but sawde-agglomeration.

TABLE 1 Milling conditions and parametric effect on particle size andshape Shape of the particles Shape of the clusters Dry Milling 12 hoursPlate-like with sharp edges Sharp and irregular 24 hours Plate-like withround edges More or less rounded 48 hours Spherical Globular clustersWet Milling 12 hours Thin plates with sharp edges Thing plates withsharp edges 24 hours Thin plates with sharp edges Thin plates with sharpedges 48 hours Thin plates with sharp edges Thin plates with sharp edges

TABLE 2 Effect of milling media on resultant size (starting sizesub-micron) shape, and agglomeration of particles Dry milled PropertiesDry Alcohol Oil and oil milled Clusters size (nm) 100 300 200 100Particle size (nm)  30  80  80  30 Agglomeration High Very less Veryless Very less Shape of the Spherical Platelet Platelet Sphericalparticles

FIG. 3 shows TEM micrographs of the as-available (700 nm), air milled,and hybrid milled (48 hrs in air medium followed by 48 hours in oilmedium) MoS₂ nanoparticles. Panel (A) represents micron-sized particlechunks of the as-available MoS₂ sample off the shelf. These micrographs,particularly panel (B), represent agglomerates of lubricantnanoparticles when milled in the air medium. Panel (B) clearlydemonstrates size reduction in air milled MoS₂. Higher magnification(circular regions) revealed formation of the disc shaped nanoparticlesafter milling in the air medium. From panels (C) and (D) it may beconcluded that the particle size was reduced to less than 30 nm aftermilling in air and hybrid conditions. Regardless of the occasionallyobserved clusters, the average size of the clusters is less than orequal to 200 nm.

Hybrid milled samples were dispersed in paraffin oil (from Walmart) andremained suspended without settling. However, the dispersion was notuniform after a few weeks. To stabilize the dispersion and extend theanti-wear properties, phospholipids were added. Around 2% by weight ofsoy lecithin phospholipids (from American Lecithin) was added in thebase oil.

FIGS. 4 and 5 show the XRD and XPS spectra of MoS₂ before and after ballmilling, respectively. XRD spectra revealed no phase change as well asno observable amorphization in the MoS₂ after milling. This observationis consistent with the continuous platelets observed throughout thenanoparticle matrix in TEM analysis for milled material. Broadening ofpeaks (FWHM) was observed in XRD spectra of MoS₂ ball milled in air andhybrid media, respectively. The peak broadening may be attributed to thereduction in particle size. The estimated grain size is 6 nm. Thisfollows the theme of ball milling where clusters consist of grains andsub-grains of the order of 10 nm. XPS analysis was carried out to studythe surface chemistry of the as-available and hybrid milled MoS₂nanoparticles. As shown in FIG. 5, a carbon (C) peak observed at 285 eVin the as-available MoS₂ sample shifted to 286.7 eV. Bonding energies of286 eV and 287.8 eV correspond to C—O and C═O bond formation,respectively. The observed binding energy level may demonstrate that athin layer containing mixed C—O & C═O groups enfolds the MoS₂ particles.

Preliminary tribological tests on the synthesized nanoparticles wereperformed on a four-ball machine by following ASTM 4172. The balls usedwere made of AISI 52100 stainless steel and were highly polished. FourBall Wear Scar measurements using ASTM D4172 were made under thefollowing test conditions:

Test Temperature, ° C. 75 (±1.7) Test Duration, min 60 (±1)   SpindleSpeed, rpm 1,200 (±60)   Load, kg 40 (±0.2)Wear scar diameter (WSD, mm) of each stationary ball was quantified inboth vertical and horizontal directions. The average value of WSD from 3independent tests was reported within ±0.03 mm accuracy.

Four Ball Extreme Pressure measurements using ASTM D2783 were made underthe following test conditions:

Test Temperature, ° C. 23 Test Duration, min 60 (±1) Spindle Speed, rpm1,770 (±60)   Load, kg Varies, 10-sec/stage Ball Material AISI-E52100Hardness 64-66 Grade 25EP

Three different particles (in w/w ratio) were evaluated for theiranti-wear properties as additives in paraffin oil. FIG. 6(A) shows theaverage wear scar measurements for paraffin oil without a nanoparticleadditive, paraffin oil with micron sized MoS₂, paraffin oil with MoS₂that was milled in air for 48 hours, and paraffin oil with MoS₂ that wasmilled in air for 48 hours followed by milling in canola oil for 48hours. FIG. 6(B) shows the load wear index for paraffin oil without ananoparticle additive, paraffin oil with micron sized MoS₂, paraffin oilwith MoS₂ that was milled in air for 48 hours, and paraffin oil withMoS₂ that was milled in air for 48 hours followed by milling in canolaoil for 48 hours. FIG. 6(C) shows the COF for paraffin oil without ananoparticle additive, paraffin oil with micron sized MoS₂, paraffin oilwith MoS₂ that was milled in air for 48 hours, and paraffin oil withMoS₂ that was milled in air for 48 hours followed by milling in canolaoil for 48 hours. FIG. 6(D) shows the extreme pressure data for paraffinoil with micron sized MoS₂, paraffin oil with MoS₂ that was milled inair for 48 hours, and paraffin oil with MoS₂ that was milled in air for48 hours followed by milling in canola oil for 48 hours. In each testthe nanoparticle additive was present in the amount of 1% by weight.

Test data from nanoparticle composition additive in base oil SolidLubricant Four Ball Tests at 40 kg Load Four Ball Extreme Pressure (ASTMD4172) (ASTM D-2783) All dispersions diluted to x % WSD Weld Load LoadWear FIG. 6(A) by wt. in reference base oil (mm) COF (kg) Index and 6(B)Paraffin oil 1.033 0.155 126 12.1 A Nanoparticles of MoS₂ without 1.0120.102 100 16.1 B organic medium (0.5%) Nanoparticles of MoS₂ without0.960 0.114 126 20.8 C organic medium (1.0%) Nanoparticles of MoS₂without 0.915 0.098 126 22.0 D organic medium (1.5%) Conventionalavailable micro 1.009 0.126 160 22.0 E particles (0.5%) Conventionalavailable micro 0.948 0.091 126 19.1 F particles (1.0%) Conventionalavailable micro 0.922 0.106 126 16.5 G particles (1.5%) NanoGlide:Nanoparticles 0.451 0.077 160 24.8 H of MoS₂ with organic medium (0.5%)NanoGlide: Nanoparticles 0.461 0.069 200 25.9 I of MoS₂ with organicmedium (1.0%) NanoGlide: Nanoparticles 0.466 0.075 315 34.3 J of MoS₂with organic medium (1.5%)

The transfer film in the wear scar, studied using energy dispersivex-ray analysis (EDS), identified the signatures of phosphates inaddition to molybdenum and sulfur. Panel (a) of FIG. 9 depicts the basecase of paraffin oil without a nanoparticle additive. Panel (b) of FIG.9 depicts paraffin oil with the molybdenum disulfide nanoparticles andthe emulsifier. It shows the early evidences of molybdenum (Mo)-sulfur(S)-phosphorous (P) in the wear track. Iron (Fe) is seen in panels (a)and (b) of FIG. 9, as it is the material of the balls (52100 steel) inthe four-ball test. The molybdenum and sulfur peaks coincide and are notdistinguishable because they have the same binding energy. Elementalmapping also showed similar results.

Prophetic Examples

Examples 2-23 are made using a similar method as Example 1, unlessspecified otherwise.

Example 2

MoS₂ (Alfa Aesar, 98% pure, 700 nm average particle size) and canola oilfrom ADM are used as the starting materials. The MoS₂ powder is ballmilled for various time conditions, variable ball/powder ratios, andunder various ambient conditions, starting with air, canola oil and thesubsequent combination of milling in air followed by milling in canolaoil. It is also ball milled in different types of organic media. Forexample, one organic medium that is used is canola oil methyl ester. Theprocessing of this will be similar to the above mentioned example.

Different types of ball milling processes can be used. For instance, inthe first step, cryo ball milling in air followed by high temperatureball milling in an organic medium is used.

After the ball milling, the active EP-EA (extremepressure—environmentally acceptable) particles are treated withphospholipids that have been mixed with a base oil such as paraffin oil.

Example 3

Molybdenum disulphide is ball milled with boron using a ratio of 1 partmolybdenum disulphide to 1 part boron. This mixture is then ball milledwith vegetable oil (canola oil) using a ratio of 1 part solid lubricantnanoparticles to 1.5 parts canola oil. An emulsifier is added using aratio of 1 part solid lubricant nanoparticle composition(MoS₂-boron-canola oil) to 2 parts emulsifier. This is added to the baseoil (paraffin oil).

Example 4

Molybdenum disulphide is ball milled with copper using a ratio of 1 partmolybdenum disulphide to 1 part metal. This mixture is then ball milledwith vegetable oil (canola oil) using a ratio of 1 part solid lubricantnanoparticles to 1.5 parts canola oil. An emulsifier is added using aratio of 1 part solid lubricant nanoparticle composition(MoS₂-copper-canola oil) to 2 parts emulsifier. This is added to thebase oil (paraffin oil).

Example 5

A molybdenum disulphide/graphite (obtained from Alfa Aesar) mixture inthe ratio of 1:1 is ball milled. This mixture is then ball milled withvegetable oil (canola oil) using a ratio of 1 part solid lubricantnanoparticles to 1.5 parts canola oil. An emulsifier is added using aratio of 1 part solid lubricant nanoparticle composition(MoS₂-graphite-canola oil) to 2 parts emulsifier. This is added to thebase oil paraffin oil).

Example 6

A molybdenum disulphide/boron nitride (Alfa Aesar) mixture in the ratioof 1:1 mixture is ball milled. This mixture is then ball milled withvegetable oil (canola oil) using a ratio of 1 part solid lubricantnanoparticles to 1.5 parts canola oil. An emulsifier is added using aratio of 1 part solid lubricant nanoparticle composition (MoS₂-boronnitride-canola oil) to 2 parts emulsifier. This is added to the base oil(paraffin oil).

Example 7

A molybdenum disulphide/graphite/boron nitride mixture in the ratio1:1:1 is ball milled. This mixture is then ball milled with vegetableoil (canola oil) using a ratio of 1 part solid lubricant nanoparticlesto 1.5 parts canola oil. An emulsifier is added using a ratio of 1 partsolid lubricant nanoparticle composition (MoS₂-graphite-boronnitride-canola oil) to 2 parts emulsifier. This is added to the base oil(paraffin oil).

Example 8

A molybdenum disulphide/graphite mixture in the ratio of 1:1:1 is ballmilled. This mixture is then ball milled with vegetable oil (canola oil)using a ratio of 1 part solid lubricant nanoparticles to 1.5 partscanola oil. An emulsifier is added using a ratio of 1 part solidlubricant nanoparticle composition (MoS₂-graphite-boron-canola oil) to 2parts emulsifier. This is added to the base oil (paraffin oil).

Example 9

A molybdenum disulphide/graphite mixture in the ratio of 1:1 is ballmilled with copper using a ratio of 1 part molybdenumdisulphide/graphite to 1 part metal. This mixture is then ball milledwith vegetable oil (canola oil) using a ratio of 1 part solid lubricantnanoparticles to 1.5 parts canola oil. An emulsifier is added using aratio of 1 part solid lubricant nanoparticle composition(MoS₂-graphite-copper-canola oil) to 2 parts emulsifier. This is addedto the base oil (paraffin oil).

Example 10

A molybdenum disulphide/boron nitride mixture in the ratio of 1:1 isball milled with boron using a ratio of 1 part molybdenumdisulphide/boron nitride to 1 part metal. This mixture is then ballmilled with vegetable oil (canola oil) using a ratio of 1 part solidlubricant nanoparticles to 1.5 parts canola oil. An emulsifier is addedusing a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-boron nitride-boron-canola oil) to 2 parts emulsifier. This isadded to the base oil (paraffin oil).

Example 11

A molybdenum disulphide/boron nitride mixture in the ratio of 1:1mixture is ball milled with copper using a ratio of 1 part molybdenumdisulphide/boron nitride to 1 part metal. This mixture is then ballmilled with vegetable oil (canola oil) using a ratio of 1 part solidlubricant nanoparticles to 1.5 parts canola oil. An emulsifier is addedusing a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-boron nitride-copper-canola oil) to 2 parts emulsifier. This isadded to the base oil (paraffin oil).

Example 12

A molybdenum disulphide/boron nitride/graphite mixture in the ratio of1:1:1 is ball milled with boron using a ratio of 1 part molybdenumdisulphide/boron nitride/graphite to 1 part metal. This mixture is thenball milled with vegetable oil (canola oil) using a ratio of 1 partsolid lubricant nanoparticles to 1.5 parts canola oil. An emulsifier isadded using a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-boron nitride-graphite-boron-Canola oil) to 2 parts emulsifier.This is added to the base oil (paraffin oil).

Example 13

A molybdenum disulphide/boron nitride/graphite in the ratio of 1:1:1 isball milled with copper using a ratio of 1 part molybdenumdisulphide/boron nitride/graphite to 1 part metal. This mixture is thenball milled with vegetable oil (canola oil) using a ratio of 1 partsolid lubricant nanoparticles to 1.5 parts canola oil. An emulsifier isadded using a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-boron nitride-graphite-copper-canola oil) to 2 parts emulsifier.This is added to the base oil (paraffin oil).

Example 14

Molybdenum disulphide is ball milled with polytetrafluoroethylene(Teflon®) in a ration of 1 part molybdenum disulphide to 1 part Teflon®.This mixture is then added to the base oil (paraffin oil) with aphospholipid emulsifier (soy lecithin).

Example 15

Molybdenum disulphide is ball milled with polytetrafluoroethylene(Teflon®) in a ration of 1 part molybdenum disulphide to 1 part Teflon®.This mixture is then added to the base oil (paraffin oil) with aphospholipid emulsifier (soy lecithin).

Example 16

Molybdenum disulphide is ball milled with metal additives like copper,silver, lead etc. in a ratio of 1 part molybdenum disulphide to 1 partmetal additive. This mixture is further ball milled in vegetable oilbased esters (canola oil methyl esters) in a ratio of 1 part solidlubricant nanoparticles to 1.5 parts esters. An emulsifier is addedusing a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-esters) to 2 parts phospholipid emulsifier. This is added to thebase oil (paraffin oil).

Example 17

Molybdenum disulphide is ball milled with metal additives like copper,silver, lead etc. in a ratio of 1 part molybdenum disulphide to 1 partmetal additive. This mixture is further ball milled in vegetable oilbased esters (canola oil methyl esters) in a ratio of 1 part solidlubricant nanoparticles to 1.5 parts esters. This is added to the baseoil (paraffin oil).

Example 18

Molybdenum disulphide is ball milled. The solid lubricant nanoparticlesare further ball milled in vegetable oil based esters (canola oil methylesters) in a ratio of 1 part solid lubricant nanoparticles to 1.5 partsesters. An emulsifier is added using a ratio of 1 part solid lubricantnanoparticle composition (MoS₂-esters) to 2 parts phospholipidemulsifier. This is added to the base oil (paraffin oil).

Example 19

Molybdenum disulphide is ball milled. The solid lubricant nanoparticlesare further ball milled in vegetable oil based esters (canola oil methylesters) in a ratio of 1 part solid lubricant nanoparticles to 1.5 partsesters. This is added to the base oil (paraffin oil).

Example 20

Molybdenum disulphide is ball milled with metal additives like copper,silver, lead etc. in a ratio of 1 part molybdenum disulphide to 1 partmetal additive. This mixture is further ball milled in fatty acids(oleic acid) in a ratio of 1 part solid lubricant nanoparticles to 1.5parts fatty acids. An emulsifier is added using a ratio of 1 part solidlubricant nanoparticle composition (MoS₂-oleic acid) to 2 partsphospholipid emulsifier. This is added to the base oil (paraffin oil).

Example 21

Molybdenum disulphide is ball milled with metal additives like copper,silver, lead etc. in a ratio of 1 part molybdenum disulphide to 1 partmetal additive. This mixture is further ball milled in fatty acids(oleic acid) in a ratio of 1 part solid lubricant nanoparticles to 1.5parts fatty acids. This is added to the base oil (paraffin oil).

Example 22

Molybdenum disulphide is ball milled. The solid lubricant nanoparticlesare further ball milled in fatty acids (oleic acid) in a ratio of 1 partsolid lubricant nanoparticles to 1.5 parts fatty acids. An emulsifier isadded using a ratio of 1 part solid lubricant nanoparticle composition(MoS₂-oleic acid) to 2 parts phospholipid emulsifier. This is added tothe base oil (paraffin oil).

Example 23

Molybdenum disulphide is ball milled. The solid lubricant nanoparticlesare further ball milled in fatty acids (oleic acid) in a ratio of 1 partsolid lubricant nanoparticles to 1.5 parts fatty acids. This is added tothe base oil (paraffin oil).

1-70. (canceled)
 71. A lubricant nanoparticle coating comprising amultifunctional additive macromolecule comprising: a plurality oflubricant nanoparticles having an open-ended architecture; and anorganic medium intercalated in the nanoparticles; wherein at least aportion of the nanoparticles have an average particle dimension of lessthan or equal to about 500 nm; and wherein the coating is in contactwith at least a portion of a surface of an object.
 72. The coating ofclaim 71, wherein the coating is in contact with a mating surface of theobject.
 73. The coating of claim 72, wherein the mating surface of theobject comprises one or more threads.
 74. The coating of claim 73,wherein the object comprises a drill pipe or a drill pipe connector. 75.The coating of claim 71, wherein the coating comprises grease.
 76. Thecoating of claim 71, wherein the coating is a greaseless coating. 77.The coating of claim 71, wherein the organic medium comprises analcohol.
 78. The coating of claim 71, wherein the coating furthercomprises at least one material from the group consisting of: ananti-corrosive, a torque modifier, an anti-oxidant, a lubricant, anemulsifier, and a dispersant.
 79. The coating of claim 71, wherein thecoating further comprises a base.
 80. The coating of claim 79, whereinthe base comprises one or more of an oil, a grease, a plastic, apolymer, a gel, a spray, a plasticizer, a hydrocarbon oil, a vegetableoil, a corn oil, a peanut oil, a canola oil, a soybean oil, a mineraloil, a paraffin oil, a synthetic oil, a petroleum gel, a petroleumgrease, a hydrocarbon gel, a hydrocarbon grease, a lithium based grease,a fluoroether based grease, an ethylenebistearamide, a wax, and asilicone.
 81. The coating of claim 71, wherein the coating furthercomprises an emulsifier.
 82. The coating of claim 71, wherein thecoating further comprises a biocidal.
 83. The coating of claim 71,wherein the coating further comprises a plurality of submicron particlesand micro particles.
 84. A lubricant nanoparticle coating comprising amultifunctional additive macromolecule comprising: a plurality oflubricant nanoparticles having an open-ended architecture; and anorganic medium intercalated in the nanoparticles; wherein at least aportion of the nanoparticles have an average particle dimension of lessthan or equal to about 500 nm; and wherein the coating is a greaselesscoating in contact with one or more threads of a drill pipe or a drillpipe connector.
 85. A method comprising: applying a coating to at leasta portion of a surface of an object, the coating comprising amultifunctional additive macromolecule comprising: a plurality oflubricant nanoparticles having an open-ended architecture; and anorganic medium intercalated in the nanoparticles; and wherein at least aportion of the nanoparticles have an average particle dimension of lessthan or equal to about 500 nm.
 86. The method of claim 85, whereinapplying the coating to at least a portion of the surface of the objectcomprises applying the coating to a mating surface of the object. 87.The method of claim 86, wherein the mating surface of the objectcomprises one or more threads.
 88. The method of claim 87, wherein theobject comprises a drill pipe or a drill pipe connector.
 89. The methodof claim 85, wherein the coating comprises grease.
 90. The method ofclaim 85, wherein the coating is a greaseless coating.
 91. The method ofclaim 85, wherein the organic medium comprises an alcohol.
 92. Themethod of claim 85, wherein the coating further comprises ananti-corrosion material.
 93. The method of claim 85, wherein the coatingfurther comprises a base.
 94. The method of claim 93, wherein the basecomprises one or more of an oil, a grease, a plastic, a polymer, a gel,a spray, a plasticizer, a hydrocarbon oil, a vegetable oil, a corn oil,a peanut oil, a canola oil, a soybean oil, a mineral oil, a paraffinoil, a synthetic oil, a petroleum gel, a petroleum grease, a hydrocarbongel, a hydrocarbon grease, a lithium based grease, a fluoroether basedgrease, an ethylenebistearamide, a wax, and a silicone.
 95. The methodof claim 85, wherein the coating further comprises an emulsifier. 96.The method of claim 85, wherein the coating further comprises abiocidal.
 97. The method of claim 85, wherein applying the coating to atleast a portion of the surface of the object comprises spraying thecoating onto at least a portion of the surface of the object.
 98. Amethod comprising: applying a coating to one or more threads of a drillpipe or a drill pipe connector, the coating comprising a multifunctionaladditive macromolecule comprising: a plurality of lubricantnanoparticles having an open-ended architecture; and an organic mediumintercalated in the nanoparticles; wherein at least a portion of thenanoparticles have an average particle dimension of less than or equalto about 500 nm; and wherein the coating is a greaseless coating.